Grouting pipe equipment and method of grouting using the same for an underground water well

ABSTRACT

Grouting equipment and methods suitable for use in underground water wells, which accomplish their goals by better centering the grouting equipment within a bore hole, even in curved bore holes, in an manner that prevents leakage of the grout into the well. Improved grouting is achieved by using corrugated, bendable incasings and expandable tubes which create a seal between the incasing and the well wall for the grout, and which prevent both contaminated surface water and grout from contaminating the groundwater. The disclosed techniques are implementable in such a manner that grouting does not necessarily need to precede the location of a groundwater nappe.

This application is a national stage filing of international applicationPCT/KR99/00458, filed Aug. 18, 1999, which claims priority to thefollowing Korean Patent Application Numbers: 1998/33646, filed Aug. 19,1998, 1998/20870U, filed Oct. 30, 1998, 1999/7981U, filed May 11, 1999,1999/11506U, filed Jun. 21, 1999, and 1999/11547U, filed Jun. 25, 1999.Priority is claimed to all of these prior applications.

FIELD OF THE INVENTION

The present invention relates to grouting pipe equipment for undergroundwater wells and grouting method wherein concrete is cured on theinterior wall of a bore hole in order to prevent contaminated surfacewater and the like from flowing in the water well.

BACKGROUND ART

A conventional arrangement for the extraction of groundwater isillustrated in FIG. 1. This arrangement includes:

an outcasing 1, which is installed to prevent the stratum of weatheredrock from collapsing into the well. The outcasing 1 is installedfollowing the drilling of the earth from the surface to a bedrock layerwith a well drilling machine;

an incasing 3, which is installed to prevent an inflow of surface water.The incasing 3 is installed after installation of the outcasing 1 andsubsequent to further drilling of the bedrock layer until a nappe ofgroundwater is reached;

a strainer pipe 18, which is installed at a position beneath theincasing 3, to allow an influx of groundwater while preventing influx ofsoil, sand, or other foreign substances;

concrete (not shown), which is injected and cured into the space formedbetween the incasing 3 and the wall of the water well, to furtherprevent influx of soil, sand, or other foreign substances;

a water pump 20, which is installed inside the incasing 3;

a water-lifting pipe 22, which is connected to the water pump 20 to liftthe groundwater out of the well, and which further includes an upperlevel sensor 53 and a lower level sensor 54 which enable groundwater tobe extracted from the well when the groundwater table is at levelspredetermined by the sensors;

a water gauge pole (34), which allows the water table in the well to bemonitored at certain depths.

In this conventional arrangement, often the outcasing 1 is too shallow,ending for example at around the middle of the weathered rock layer,when it should be embedded into the bedrock layer. Indeed, sometimesbores have been intentionally formed on the outcasing to allow surfacewater to flow into the well. Furthermore, synthetic resin incasings aresometimes not installed in a given water well, or if installed, are notgrouted. Accordingly, prior art approaches have allowed polluted surfacewater to flow into groundwater water wells, resulting in pollution ofthose wells.

Of the above scenarios, a most common problem is the insertion of anincasing without the use of a subsequent grouting process. This oftenoccurred because it was essentially impossible to restrict the depth ofthe insertion of the incasing, and hence the depth of the concrete.

In another conventional technique for preventing permeation of surfacewater, a bore hole is drilled to the surface of a bedrock layer, and anoutcasing is installed. Thereafter, concrete is injected and curedinside of the outcasing, and then further excavation is performed untila nappe of groundwater is reached, thus forming another bore hole of asmaller diameter to accommodate an incasing. However, this method isinefficient because the grouting process must be performed withoutknowing the quantity, if any, of the groundwater available at the wellsite. In other words, the possibility is raised that the well would needto be abandoned as unsuccessful after the expensive process of groutinghas been performed.

To solve this particular problem alternative methods have beenimplemented. Specifically, it has been attempted to drill to the upperlayer of a bedrock stratum to insert an outcasing. Then, to accommodatethe subsequent placement of an incasing, the drilling bit has beenchanged to a smaller diameter to allow drilling to continue until anappe of groundwater is reached. Thereafter, concrete is grouted intothe annular space between the incasing and the interior wall of thedrilled bore hole to prevent influx of surface water.

This method however is problematic because it is difficult to grout theconcrete in the lower portions of the well. Moreover, even if it ispossible to grout the lower portions, the groundwater will becontaminated by leakage of the concrete into the well. Furthermore,because the annular space that the concrete fills is typically narrow,for example, about 50-60 mm in width, the concrete may “bridge” at someintermediate point in the space and prevent the space from being fullygrouted when concrete is introduced from the top of the well.Additionally, if the water table has already risen in the well, theconcrete would be diluted by blending with the groundwater present inthe annular space, rendering it impossible to cure the concrete to asufficient strength. To ensure water quality, the grouting process wouldtherefore have to be implemented repeatedly, for example, twice orthrice, resulting in enormous additional construction expenses.

Another alternative approach used in the art has been to drill into thebedrock layer, confirm the presence of groundwater, and then to fill thewell with sand from the depth of the nappe to a certain height withinthe well. Thereafter, lumps of clay or wooden boards are placed on thesand to seal the groundwater, and concrete is then grouted. Excavationcan then be continued by removing and discharging the clay, the woodenboards, and the sand until the water is again reached, and then anincasing is inserted.

This approach too suffers from problems. If the central axis of theincasing does not coincide with the shaft of the pre-drilled bore hole,it will be impossible to use. Furthermore, if the sealing materials donot adequately seal of the groundwater, concrete may be injected eveninto the nappe, and may even cut the nappe off. Hence, the quality andquantity of attainable water is considerably decreased.

In addition to these problems encountered in the prior art, conventionalmethods suffer from the fact that when a bore hole is drilled, the borehole may be curved to some extent because of the different constituentsof the bedrock layer. In other words, the central axis of the bore holewill not be straight, making insertion of the incasing difficult orimpossible, thus resulting in inferior grouting. Additionally, theconcrete in conventional methods may infiltrate the nappe, thus eithercontaminating the water or reducing its quantity. This results becausethe dependability of the cutoff or sealing means cannot be adequatelysecured to protect the nappe from the concrete.

Also, these prior art approaches generally contemplate use with wells oflarger diameters, and are therefore of limited utility in makingunderground water wells to service individual houses in rural villages,farms, and other small-scale constructions, which generally are lessthan 50 mm in diameter. The problems of the prior art are exacerbatedfor wells of such small sizes.

SUMMARY OF THE INVENTION

The disclosed embodiments of the invention provide grouting pipeequipment and easy and efficient grouting methods suitable for use inunderground water wells. The various embodiments accomplish this resultby better centering the grouting equipment within a bore hole, even incurved bore holes, in an manner that prevents leakage of the grout intothe well. Improved grouting is achieved by using corrugated, bendableincasings and expandable tubes which create a seal between the incasingand the well wall for the grout, and which prevent both contaminatedsurface water and grout from contaminating the groundwater. Thedisclosed techniques are implementable in such a manner that groutingdoes not necessarily need to precede the location of a groundwaternappe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of conventional groundwater extractionequipment.

FIG. 2 is a cross-sectional view of the grouting pipe equipmentaccording to a first embodiment of the invention.

FIG. 3 is a higher magnification cross-sectional view of the incasing ofthe first embodiment.

FIG. 4 is a plan view of the incasing of the first embodiment.

FIG. 5 is a perspective view of the cutting portion of the firstembodiment.

FIG. 6 is a cross-sectional view of the grouting pipe equipmentaccording to a second embodiment of the invention.

FIG. 7 is a higher magnification cross-sectional view of the incasing ofthe second embodiment.

FIG. 8 is a plan view of the incasing of the second embodiment.

FIG. 9 is a perspective view of the connection portion of the secondembodiment.

FIG. 10 is a perspective view of the tube band of the second embodiment.

FIG. 11 is a cross-sectional view of the grouting pipe equipmentaccording to a third embodiment of the invention.

FIG. 12 is a higher magnification cross-sectional view of the incasingof the third embodiment.

FIG. 13 is a perspective and cross-sectional view of the connectionportions of the incasing of the third embodiment.

FIG. 14 is a cross-sectional view of the grouting pipe equipmentaccording to a fourth embodiment of the invention.

FIG. 15 is a cross-sectional view showing the installation of anexpansion tube of the fourth embodiment.

FIG. 16 is a cross-sectional view of the check valve of the fourthembodiment.

FIG. 17 is a perspective view of the check valve of the fourthembodiment.

FIG. 18 is a plan view of a well mounted with a drilling bit guidingdevice and an expansion tube according to a fifth embodiment of theinvention.

FIG. 19 is a cross-sectional view of the equipment shown in FIG. 18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A. First Embodiment

FIGS. 2 through 5 disclose a first embodiment for a groundwater well andits associated grouting equipment, which includes:

an outcasing 1 that is installed in a part of the weathered rock layerand the bedrock layer;

an incasing 3 for preventing an influx of contaminated surface water,which is spaced from the inner wall of the bore hole. Incasing 3 alsoincludes corrugation tubes 12 at fixed intervals to allow the incasingto be inserted into a curved bore hole (as shown);

bearings 16 installed at fixed intervals on the exterior of the incasing3;

a strainer pipe 18 installed under the incasing 3 to filter particulatesfrom the groundwater, and formed with bendable corrugation tubes 12;

a well pump 20 installed inside the incasing 3 to extract thegroundwater;

a water-lifting pipe 22 connected to the well pump 20 to transport thegroundwater to the ground level;

an expansion tube 5 installed at a section of a reduced diameter 14 ofthe lower potion of said incasing 3;

a rubber tube 51 installed at an outer circumference of the expansiontube 5 to securely attach the expansion tube 5 to the outer periphery ofthe incasing 3 before expansion, and to permit for uniform expansion;

a compressed-fluid injection hose 7 installed in the interior orexterior of the incasing 3 and connected to the expansion tube 5 toprovide a compressed fluid from the ground level to said expansion tube5;

a compressed-fluid injection hose cutting mechanism: with reference toFIGS. 3 and 5, a cutting blade 28, a guide 30 for guiding the cuttingblade 28, and a cutting portion 56 furnished with a passage hole 67 areattached to the interior of the incasing 3. These structures provide amechanism for cutting the compressed-fluid injection hose 7 when thathose is installed in the interior of the incasing 3. Passage hole 67holds the hose 7 steady during the cutting process. Cutting is achievedby pulling on a string 32 which is connected to the cutting blade 28,and which may be pulled by an operator on the ground level;

a soft cover plate 24 installed over the expansion tube 5 to protect theexpansion tube 5 from the overlying concrete;

a liquid-grout supply tube 26 installed in the interior of incasing 3 toinject concrete from the ground level to between the incasing 3 and thebore hole;

upper and lower level sensors 53 and 54; and

a water gauge pole 34.

B. The Second Embodiment

FIGS. 6 through 10 disclose a second embodiment for a groundwater welland its associated grouting equipment. The structure and/or operation ofthose elements common to the first embodiment are not again summarized.The second embodiment includes:

an outcasing 1;

an incasing 3 with corrugation tubes 12;

a plate spring 82 installed on the exterior of the incasing 3 tomaintain a fixed space between the bore hole and the incasing 3, thespring 82 being outwardly circular-shaped and attached only at its lowerportion (see FIG. 7);

a strainer pipe 18 with corrugation tubes;

a well pump 20;

a water-lifting pipe 22;

an expansion tube 5;

tube bands 94 for fixing the expansion tube 5 to the exterior of theincasing 3, as shown at FIG. 10. The tube band 94 is formed of a metalbelt having several vents 70 on one side, and on the other side, awelded metal bar 61 which has an width equal the metal belt. Aprotrusion part(s) 78 is formed for insertion into the vents 70 when theperiphery of the tube 5 is covered with and coiled around the tube band94. Any overlapping portion of the metal bar 61 can be fixed to the beltby deforming fixing clip 60.

a protective expansion tube 57 installed at the outer periphery of aninternal expansion tube 58 to allow the expansion tube 5 to be expandeduniformly and ensure proper shielding even at the reduced diameterportion 14 of the incasing 3;

a compressed-fluid injection hose 7;

a soft cover plate 24; and

a liquid-grout supply tube 26.

Also shown, in FIG. 9, is a method for connecting or extending twoportions of incasing 3. In this regard, lower connection portion 86 andupper connection portion 85, which appear at the ends of two sections ofincasing 3 pipe, are shown. As FIG. 9 shows, lower connection portion 86has a slightly larger diameter than the corresponding portion of upperconnection portion 85. When connected, a number of vertically elongatedprotrusions 90 on upper portion 85 are fitted into corresponding cutparts 87 appearing on lower portion 86. After connected, the twoportions 85 and 86 are bolted at matching bolt holes 89.

C. Methods of Constructing and Using the First and Second Embodiments

1. First Method

When using either the first or second embodiments described above, thefirst step, in a first method, is to excavate the weathered rock layerand, at least partially, the bedrock layer using a drilling bit of arelatively large diameter. Thereafter, the outcasing 1 is installed onthe inner wall of the bore hole to prevent collapse of the bore hole andinflux of the contaminated surface water. Next, a drilling bit of asmaller diameter is used to excavate further until groundwater islocated. Then, the strainer pipe 18 is inserted and installed in thegroundwater, followed by the insertion of the incasing 3 into the upperportion of said strainer pipe 18.

With the help of the bearings 16 (first embodiment) or plate springs 82(second embodiment), and the corrugation tubes 12, the incasing 3 can beinserted easily even into a curved bore hole without scraping or gettingstuck to the bore hole. Additionally, bearings 16 or plate springs 82position the incasing 3 with a constant annular space from the borehole.

When the incasing 3 is installed properly, compressed fluid is injectedthrough the compressed-fluid injection hose 7 into the expansion tube 5mounted at the lower periphery of the incasing 3. This causes theexpansion tube 5 to expanded uniformly with the assistance of the rubbertube 51 (first embodiment), or the internal expansion tube 58 inconjunction with the protective expansion tube 57 (second embodiment),such that the expansion tube 5 serves as a shielding plate. Thus, whencompressed fluid is injected into said expansion tube 5, the gap betweenthe incasing 3 and the inner wall of the bore hole becomes sealed andthe groundwater is thus protected from contamination. Once this firstsealing is completed, liquid grout (i.e., concrete) is provided throughthe liquid-grout supply tube 26 and is cured.

2. Second Method

When using either the first or second embodiments described above, thefirst step, in a second method, is to excavate the weathered rock layerand, at least partially, the bedrock layer using a drilling bit of arelatively large diameter. Thereafter, the outcasing 1 is installed onthe inner wall of the bore hole to preventing collapse of the bore holeand influx of the contaminated surface water. Once the installation ofthe outcasing 1 is completed, the incasing 3 is installed, and theexpansion tube 5 is expanded as discussed above to guarantee a secureshielding.

A bore hole is then excavated to the groundwater nappe in the bedrocklayer using a drilling bit of a small diameter. When groundwater islocated, liquid grout is injected into the bottom of the annular spaceexterior to the incasing 3. Again, the expansion tube 5 provides a goodseal between the grout and the groundwater.

For either of these two methods, it should be noted that the liquidgrout supply tube 26, like the compressed-fluid injection hose 7, can beprovided in the interior of incasing 3 (as shown in FIG. 3), or can beprovided in the annular space exterior to the incasing 3 (as shown inFIG. 7), if that space is of a sufficient width. Likewise, if the liquidgrout supply tube 26 is mounted on the interior, it may be cut using thecutting blade 28, the pulling string 32, and the guide 30 after curingof the concrete is completed, as explained earlier with reference to thecompressed fluid injection hose 7.

Using these methods, contaminated surface water is introduced into thewell because the liquid concrete is provided through the liquid-groutsupply tube 26 in such a way that it pushes the contaminated surfacewater present in the annular space between the incasing 3 and the borehole up toward the surface. Additionally, better curing is achievedbecause “bridging” or incomplete compaction of the concrete does notoccur. Further, the soft cover plate 24, possibly including the internalexpansion tube 58 and the protective expansion tube 57 (secondembodiment), protects the expansion tube 5 from damage when the liquidconcrete is injected. When the construction is completed as describedabove, the water-lifting pipe 22 and the well pump 20 can be installedinside the incasing 3, thereby allowing pumping of groundwater.

D. Third Embodiment

FIGS. 11 through 13 disclose a third embodiment for a groundwater welland its associated grouting equipment. Referring to FIG. 12, the lowerpart of the incasing 3 is provided with a shielding pipe 55 having agiven length. The upper and lower part of the pipe 55 are respectivelylocated in proximity to an upper protective circular board 36 and alower protective circular board 38, both of which have a larger diameterthan that of the shielding pipe 55. The outer periphery of the shieldingpipe 55 is provided with an expansion tube 5. The expansion tube 5 isprotected by the upper protective circular board 36 and the lowerprotective circular board 38, which act to prevent damage to expansiontube 5 when the incasing pipe is subsequently inserted into the borehole. In addition, the outer periphery of the lower protective circularboard 38 is provided with bearings 16, which serves as a guide when theincasing 3 is inserted. Again, plate springs 82 (see FIG. 11) keep aconstant distance between the incasing 3 and the internal wall of thebore hole, so that thickness of the grouted concrete can be keptconstant even in a curved bore hole. As in the first embodiment, a softcover plate 24 is provided between the upper protective circular board36 and the expansion tube 5, and a rubber band 51 is provided outsidethe expansion tube 5 to protect the expansion tube 5 and to effectuateuniform expansion thereof. Likewise, as in the first embodiment, acompressed-fluid injection hose 7 is connected to the expansion tube 5exterior to the incasing 3, and a soft liquid grout supply tube 26 isprovided exterior to the incasing 3.

As another variation, as shown in FIG. 11, the compressed-fluidinjection hose 7 is connected to the expansion tube 5 via outside of theincasing 3. According to this variation, the intake of the expansiontube 5 is made by incising the body of the incasing 3 partially in avertical direction, by inserting the compressed-fluid injection hose 7into the incision part, and by welding the hose 7 in place. Thisprocedure is facilitated when the incasing 3 and the injection hose 7are made of the same material. A connector 13 connects the weldedportion of the compressed-fluid injection hose 7 to a longer freeportion of the hose. The compressed-fluid injection hose 7 is protectedagainst impact by being coiled on its exterior with a coil spring 71.

E. Method of Constructing and Using the Third Embodiment

When using the third embodiment described above, the first step is toexcavate the weathered rock layer and, at least partially, the bedrocklayer using a drilling bit of a relatively large diameter. Thereafter,the outcasing 1 is installed on the inner wall of the bore hole topreventing collapse of the bore hole and influx of the contaminatedsurface water. Next, a drilling bit of a smaller diameter is used toexcavate further until groundwater is located. Then, the strainer pipe18 is inserted and installed in the groundwater, followed by theinsertion of the incasing 3 into the upper portion of said strainer pipe18.

The incasing 3, complete with the shielding pipe 55 and other relatedstructures, is inserted to a depth where the lower protective circularboard 38 rests on the junction formed at the interface of the largediameter bore hole and the smaller diameter bore hole. Then compressedfluid is injected to the expansion tube 5 through the injection hose 7so that the expansion tube 5 expands as previously summarized.

In this embodiment, because the difference in diameter between theshielding pipe 55 and the bore hole is relatively small, the expansiontube 5 need only expand slightly to form the seal, thus lessening thechance of damaging the expansion tube 5. When concrete is injectedthrough the liquid-grout supply tube 26, the load of the concrete isdispersed by the upper protective circular board 36 such that the loadimposed on the expansion tube 5 is reduced, further protecting theexpansion tube 5 from damage. The concrete wall cured between theincasing 3 and the bore hole is formed to be sufficiently thick toobtain a complete sealing effect.

In a variation on this technique, cement, urethane, epoxy resin, orother suitable materials may be used as the compressed fluid that isinjected into the expansion tube 5. This allows the well to be primarilysealed by fast curing of the compressed fluid. This provided a stableload for the subsequently injected concrete, which act secondarily toseal the well.

FIG. 13 discloses another method for connecting or extending theincasing 3. This variation employs an upper circumference ring 96 and alower circumference ring 97 positioned at respective ends of twosections of incasing 3. When the two sections of incasing are joined atthe rings 96 and 97, a packing 99 may be placed over them, and then thejoined structure set within semi circular couplers 98, each having a “C”shaped section. The two couplers 98 may then be bolted together asshown.

When the construction is completed as described above, the water-liftingpipe 22 and the well pump 20 can be installed inside the incasing 3,thereby allowing pumping of groundwater.

F. Fourth Embodiment

FIGS. 14 through 17 disclose a fourth embodiment for a groundwater welland its associated grouting equipment. The fourth embodiment has asimilar structure to the second embodiment, and the reader is thusdirected to the discussion of the second embodiment for a fullerdiscussion of the components that are common to both.

The fourth embodiment includes an outcasing 1, an incasing 3, a platespring 82, an expansion tube 5, a compressed fluid injection hose 7, acover plate 24, and a liquid-grout supply tube 26, as in the secondembodiment. In one difference between the two embodiments, a screwjunction part 63 is provided to allow for extension of the incasing 3.Screw junction part 63 is formed in a round screw shape to allow thejunction of pieces the incasing 3 in an easy manner.

Referring to FIG. 14, the water pump at the ground level can beconnected directly to the well equipment by applying a connectionaccessory device 62 to the uppermost end of the incasing 3. A femalescrew is provided in the upper end of the connection accessory device 62and a pressure equalizer tube 68 is provided in the incasing 3. If ahose of different material is used, a pendulum 59 can be hung on thelowermost part of the pressure equalizer tube 68 to assist in set up. Afilter barrel 64 having a check valve 72 for the pressure equalizer tube68 is provided above the tube 68 to prevent contaminants from flowinginto the well if air flows into the pressure equalizer tube 68. Acontra-injection tube 65 with a valve 66 for adjusting fluid amount isalso provided as shown and is connected to the output of the water pump.

FIG. 16 shows the lower part of the well, including the check valve 76,which is shown in FIG. 17. The check valve 76 includes a hollow slidingpole 75, a check valve seat 70, and openings 77, through whichgroundwater passes to the top of the well. The check valve is seated atthe end of the incasing 3, which is bent inwardly at its end to form alip for this purpose. Packing may also be applied between the checkvalve 76 and bent lip as is shown in FIG. 16. The hollow sliding pole isconnected to the pressure equalizer tube 68. A plate shaped check valvecircular board 69 with a cylindrical guide 74 covers the check valveseat 70 so that board 69 and the upper surface of the check valve seat21 are in close contact. Cylindrical guide 74 is stressed by a spring84. As will be explained in more detail in the next section, the checkvalve 76 helps to prevent the water level in the well from droppingexcessively.

G. Method of Constructing and Using the Fourth Embodiment

When using the fourth embodiment, the well is first drilled and groutedusing the techniques earlier described. Thereafter, the pump pipe isconnected to the connection accessory device 62 at the upper end of theincasing 3. Next, the check valve 72 and valve 66 for adjusting thefluid amount through the contra-injection tube 65 are adjusted.

When water is filled into the impeller casing of well pump 20, and whenvalve 66 is closed, groundwater is raised from a natural water level inthe incasing 3, while the water level in pressure compensation equalizertube 68 is lowered from the natural water level to prevent excessivenegative pressure in the incasing 3.

If the natural water level is low, air may flow into the well, and waterpumping may be negatively affected because air is drawn into the wellpump 20. To address this problem, some of the groundwater from the wellpump 20 is injected into the lower part of the well through the pressurecompensation equalizer tube 68 via contra-injection tube 65. Thereafter,valve 66 on the contra-injection tube 65 is closed to allow air to flowcontinuously into the well to prevent air from congesting in the wellpump 20. Thus, a balance can be achieved between groundwater flowinginto the well from the nappe and groundwater flowing into the lower partof the well through the contra-injection tube 65, so that water pumpingmay be suitably and quickly controlled.

When the well pump 20 is stopped, the water level in the well will tendto go down. The check valve 76 acts to prevent the water level fromgoing down at an excessive rate which would affect the ability of thewell pump 20 when it is later again turned on. Check valve 76 holdsgroundwater in the incasing 3 because the check valve seat 70 and thecheck valve circular board 69 are in contact because of the weight ofthe pressure compensation equalizer tube 68 and the pendulum, which istransferred to the check value circular board 69 through spring 84 whenthe pump stops. In short, keeping the incasing 3 filled with groundwatermakes the pumping operation easier to start when the pump againoperates.

If the check valve 76 has a problem, the check valve seat 70 and thecheck valve circular board 69 can easily be drawn out the well bydisassembling the upper part of the pipe connection accessory and bypulling up the pressure compensation equalizer tube 68, makingmaintenance work convenient.

H. Fifth Embodiment

FIGS. 18 and 19 disclose a fifth embodiment, more specifically a guidingdevice 31 for a drilling bit that also includes many of the groutingstructure mentioned earlier. As will be explained subsequently, thisdevice allows for a well to be partially excavated (e.g., using a largediameter drill bit), grouted, and then excavation can continue (e.g.,using a smaller diameter drill bit). Element numerals designatingstructures earlier mentioned are not further discussed for simplicity.

FIG. 18 shows a perspective view of guiding device 31 for the drillingbit, while FIG. 19 provides a cross sectional view. The inside diameterof the upper portion 33 of guiding device 31 in equal to that of theincasing 3 to simplify their connection. The inside diameter decreasessteadily from the top of the guiding device 31, resulting in an invertedcone shaped upper part. The-lower portion 35 of guiding device 31 hasthe same inside diameter through its entire height, resulting in thebody of guiding device 31 having a funnel shaped section, as shown inFIG. 19. To assist in guiding a drilling bit through the guiding device31, the inside diameter of the lower portion 35 of guiding device 31 isformed a little larger than the diameter of the drilling bit.

Hole 17 acts as an input for compressed fluid injection hose 7 and isformed in the upper portion of guiding device 33. Expansion tube 5 ispositioned on the exterior of guiding device 31 and is fixed by a tubeband 94. The expansion tube 5 comprises an outside soft expansion tubeand an inside hard expansion tube integrally formed so that a watertightseal can be obtained even when the inside wall of the groundwater wellis rough. This construction also allows for the formation of a steadyexpansion force for the tube 5. Bearings 16, formed on the lower portion35 of the guiding device 31, facilitate the insertion of the guidingdevice 31 by providing a space between the device and the well wall, andprotect the expansion tube 5 during insertion. Pulleys 93 are providedrespectively at opposite sides of the upper portion 33 of guiding device31 so that a wire rope 92 can be affixed to manipulate the device 31from outside of the well. Guidance rings 37 prevent the wire rope 92from moving off the pulleys 93.

I. Method of Constructing and Using the Fifth Embodiment

The fifth embodiment is used in operation as follows. First, a primaryexcavation using a drill bit of a large diameter is used to reach agiven depth in the bedrock. Guiding device 31 is connected to anincasing 3. Wire rope 92 is inserted to the pulleys 93 and the device islowered down to the bottom of the bore hole. As mentioned earlier, thediameter of the upper portion 33 of the guiding device 31 is the same asthe outer diameter of the incasing 3, thus making it simple to assembleor weld the two together.

After insertion into the well, compressed fluid is injected into theexpansion tube 5 to cause it to expand and create a seal against thewell wall. Through this expansion, the centers of the bore hole and theguiding device 31 are made to coincide. Additionally, this expansionprevents inflow of contaminated surface water and helps to hold theincasing 3 and guiding device 31 steady from vibrations causedsubsequent excavation. Thereafter, a bore hole of small diameter is dug.The funnel shaped body of guiding device 31 acts to place the drillingbit in a central position within the well. A cylindrical portion 90 actsto guide the small diameter drilling bit at early stages in theexcavation process.

If a groundwater nappe is located during the drilling process, the wirerope 92 is removed from the guiding device by pulling it through thepulleys 93. Thereafter, liquid grout (i.e., concrete) is injected intothe annular space and is cured. If a groundwater nappe is not found,pressure is relieved in the expansion tube 5 and the incasing 3 andguiding device 31 are drawn out of the well by pulling on both sides ofthe wire rope 92.

If the diameter of the incasing 3 has a smaller diameter than that ofthe guiding device 31, the guiding device 31 is first centered by theexpansion tube 5, and then the incasing is inserted. To ensure that thegrout fills the annular space between the incasing and the well wallwithout leakage, a round plate shaped ring 39 is welded to the end ofthe grouting pipe to which is connected a soft O-ring packing 83 (seeFIG. 19). When the incasing 3 is inserted, the O-ring packing 83contacts the guiding device 31 somewhere near the middle of its sloped(i.e., cone shaped) surface. The weight of the incasing compressesO-ring 83 to prevent leakage of the grout.

J. Conclusion

The disclosed embodiments offer the following advantages. First, anincasing can be inserted to a desired depth without being stuck even inbent bore holes. Second, reliability of the grouting is improved. Third,the expansion tube allows grouting to be performed while preventingcontamination of the groundwater and blockage of its passage into thewell. Fourth, the disclosed techniques have applicability to wellsalready exploited and wells under exploration. Fifth, the incasing canbe used as the water pumping pipe for wells of small diameter, and in amanner that prevents the influx of contaminated surface water, and whichmakes grouting relatively simple. Sixth, the centering mechanismsdisclosed herein allow for the formation of a water-proof grouted wallhaving no gaps. Seventh, excavation to the groundwater nappe is madepossible without inflow of the contaminated surface water throughunification of the grouting pipe and the body of the guiding device.Eighth, the incasing and the guiding device can be-easily drawn out of awell that has not tapped into a groundwater nappe.

What is claimed is:
 1. A system for grouting a well containing a borehole with a bore hole wall, comprising: an incasing capable of beingplaced within a bore hole to create an annular space between the borehole wall and the incasing; and an expandable tube positioned onexterior of the incasing and capable of expansion to create a seal atportion of the annular space between the incasing and the bore holewall; and a cover plate installed on the exterior of the incasing andover the expandable tube to protect the expandable tube from grout. 2.The system of claim 1, wherein the incasing further includes bendablecorrugations to allow the incasing to be inserted in non-linear boreholes.
 3. The system of claim 1, wherein the expandable tube ispositioned on the incasing at a portion of the incasing having a reduceddiameter.
 4. The system of claim 1, further including bearingspositioned on the exterior of the incasing.
 5. The system of claim 1,wherein the expandable tube is affixed to the incasing by a band.
 6. Thesystem of claim 1, wherein the expandable tube comprises an alp internalexpansion tube and a protective tube positioned exterior to the internalexpansion tube.
 7. The system of claim 1, further comprising a shieldingpipe located between the expandable tube and the incasing.
 8. The systemof claim 1, wherein the shielding pipe has an upper and lower edge, andfurther comprising circular boards attached to the exterior of theincasing, wherein the exterior boards connect to the upper and loweredges of the shielding pipe.
 9. The system of claim 1, furthercomprising a plurality of springs on the exterior of the incasing toassist in centering the incasing within the bore hole wall.
 10. Thesystem of claim 1, wherein the incasing consists of a plurality ofconnected incasing portions.
 11. The system of claim 1, furthercomprising a grout supply tube for supplying liquid grout to the annularspace above the seal formed by the expandable tube.
 12. The system ofclaim 11, wherein the grout supply tube is located in the interior ofthe incasing, and further comprising a tube cutter mounted to theinterior of the incasing for cutting the grout supply tube.
 13. Thesystem of claim 1, further comprising an injection hose for supplying amaterial to the expandable tube to promote expansion of the tube. 14.The system of claim 13, wherein the injection hose is located in theinterior of the incasing, and further comprising a hose cutter mountedto the interior of the incasing for cutting the injection hose.
 15. Thesystem of claim 13, wherein the injection hose is made of the samematerial as the incasing.
 16. The system of claim 15, wherein theinjection hose is fastened along a portion of the incasing and iscapable of supplying the material through cuts made in the incasing. 17.The system of claim 1, further comprising a strainer pipe connected tothe incasing, the strainer pipe containing bendable corrugations toallow for the insertion into non-linear bore holes.
 18. The system ofclaim 1, further comprising a well output to dispense fluid from thewell and a pressure equalizer tube, wherein the pressure equalizer tubeis capable of receiving a portion of the fluid and air to regulate thepressure within the well.
 19. The system of claim 18, further comprisinga filter in communication with the pressure equalization tube to preventairborne contaminants from entering the well through the pressureequalization tube.
 20. The system of claim 18, further comprising acontra-injection tube connected to the well output, wherein thecontra-injection tube is controllable by a valve to control the amountof fluid received by the pressure equalization tube.
 21. The system ofclaim 18, further comprising a check valve connected to the interior ofthe incasing, the check valve for controlling fluid flow in the well,wherein the check valve is controllable in part by the weight of thepressure equalization tube.
 22. A drilling bit guiding device forguiding a drill bit of a first diameter within a bore hole wall of asecond diameter, wherein the first diameter is smaller than the seconddiameter, comprising: a cylindrical body with a constant external thirddiameter, wherein the third diameter is larger than the first diameterbut smaller than the second diameter, the body containing a funnelnarrowing from the third diameter to accompany the drill bit of thefirst diameter, wherein the body is connectable to an incasing; whereinthe incasing contains a circular ring at an end of the incasing that isconnected to an o-ring, and wherein the incasing is connectable to thebody through the o-ring; and an expandable tube positioned on exteriorof the body around the third diameter and capable of expansion to createa seal at portion of an annular space between the body and the bore holewall.
 23. The guiding device of claim 22, further including bearingspositioned on the exterior of the body.
 24. The guiding device of claim22, further comprising an injection hose for supplying a material to theexpandable tube to promote expansion of the tube.
 25. The guiding deviceof claim 22, wherein the incasing has a fourth diameter between thefirst diameter and the third diameter.
 26. A method for forming astructure for a well, the well containing a first bore hole wall of afirst diameter, comprising: installing an incasing into the bore hole,the incasing containing an expandable tube positioned on exterior of theincasing, the incasing defining an annular space with respect to thebore hole wall; expanding the expandable tube to create a seal at aportion of the annular space between the incasing and the bore holewall; drilling with a drill bit of a second diameter smaller than thefirst diameter to reach a nappe; and centering the drill bit by passingthe drill bit through guiding device connected to the expanded tube. 27.The method of claim 26, further comprising filling the portion of theannular space above the expanded tube with grout.
 28. The method ofclaim 26, further comprising installing an outcasing against the borehole wall prior to installing the incasing.
 29. The method of claim 26,wherein the guiding device contains a funnel.
 30. The method of claim26, further comprising filling the portion of the annular space abovethe expanded tube with grout.